Back check for gas meters



Junejlfi, 1931. D. N. LAMBERT 1,310,835

BACK CHECK FOR GAS METERS Filed Oct. 8, 1930 Patented June 16, 1931 Tsunirse- 15m 1 s arser @rrr DAVID N. LAMBERT, or BROOKLYN, NEW YORK BACKCHECK roe 'eAs METERS Application filed October 8, 1930; Serial 481316.

Thepresent invention relates to improveback check, it being shownmounted in the ments-in gas meters andmore particularly'tohousingof'agas meter; j mechanism. for preventing reverse or back- F 2is-a'verticalsectiontaken on the'line ward operation thereof and of thedevices in 2-2 of Fig. 1, showing the back check in eledicating theamount of gas passing therevation;

through "for consumption, and the primary Fig.3 is a verticalsection-taken on the line object of the invention is to provide a'novel.3 .-3 of Fig. '1, showing diagrammatically the and improved back checkor stop for preventmanner in which the controllingpawlcomes in'gfraudulent reverse or backward opera into' engag'ement with the'stop'pawl to'set it tion of the meter and its indicatingdevices, instoppingposition when reverse op'eration so which'is noiseless'duringthe normal operao-fthe meter'occurs; i ti'on of the meter and willpermit'reverse op Fig. 4 is aview similar'to Fig. 3, but show- 'e'rationthereof to a limited but suificientexing diagrammatically the manner inwhich tent toavoid injury to the meter mechanism the controlling pawlclearsth'estop pawl should excessive back pressure be accident- Whilethe meter is-innormal-operation; and ally applied thereto. Fig. 5 is adetailperspective View ofthe Back checks have been proposed or usedcontrolling'p'awl. for -arresting reverse operation of a meter-and fSHmlar parts are designated by' the same its indicating devices, butsuch back checks reference characters in the diii'erent figures;

' have been found objectionable because of the Theinventionis 'show'n inthe present in 7i;

clicking sound they produce during the -norstance applied-tea gas-meterof awell known m'al'operation of the meter, whichis objecconventionaltype embodying a vertical ti'onable to consumers, and furthermore, thecrank 1 which is used inir'ieters -ot suchtyp'e meter mechanism wasliable to damage'or to to actuate'the valves which control the flowstrain of its working parts inthe event excesof gas to and from themeasuring bellows'or sive back pressure were-accidentally applieddiaphragms this crank,being-mo-untecl with-- to the meter outletaswhenthe temperature in the meter housingandadapted for rotaof thegas'ent'rained in the line from the metion by the usual tangent armEZ-towhich it ter to-anappliance on whichthe cock is closed isfixed. The'ta'11gent-arm,-in meters of such 30 rises and thereby causes this bodyof'gasto type, is actuated by flag Wiresand linkage so expand and increase itspressure and to flow which, in turn are actuated by the bellows backthrough the-meter, or a workman, in or diaphragms, the tangent armhaving a cleaning a gas line, inadvertently applies tangent hat 2?to'which the links-of the flag pressure tothe outlet instead or theinlet line, wires are connected whereby the crank 1 the back checksheretofore proposed or used will be rotated in a clockwisedirectionaspermitting an insufficient extent of reverse or indicated by the arrowin Fig. 1 during the backward operation of the meter mechanism normaloperation of the meter. Since the V to avoid injury thereof in suchevents. bellows or diaphragms, the flag wires and These disadvantagesare obviated by the linksbperated thereby'a'nd the gas control improvedback check or stop provided by-the valves operated-by the crankl'arewell known 7 present invention which, moreover, is simin the cart andform no part-of the present p le'in construction and reliable inoperation, invention, they arenotshown herein and furit being set intoarresting condition in a sim ther description thereof is deemedunnecesple and effective manner by gravity when re sary; r

45 verse or backward operation of the meter The crank 1 actuatestheusual dial or other 5 mechanism takes place. I mechanism forindicati'ngthe amount of gas In the accompanying drawings, which passingthrough the meter, the crank 1 show the preferred embodiment ofthein'ven usually having a worm 3 fixed thereon and ion: meshing with 'agear a which'is secured on Fig. l'is a top plan view of the improved ahorizontal shaft-"5, the latter being conits gravity in eitherthe'horizontal inoperativewith an arm 11 having a vertical slot 12therein which lies substantially at a right angle to a radius of thecrank 1, and this arm supports a pivot pin 18 on which is pivotallymounted a stop pawl .14. This stop pawl is freely movable in a verticalplane in the slot 12 through an angle of approximately it having anarrn14 at one end which is at the upper side of the supporting arm 11andis adapted to lie in an approximately horizontal position on theupper side of the arm 11 and beneath the path in which the tangent arm 2travels as shown by the full lines in Fig. 3, and it is adapted tooccupy an approximately upright position so that it projects into thepath of the tangent arm 2 as shown by the dotted lines in said figure.The end of the pawl 14 opposite to the end 14 thereof is formed with a.pair of cars 14? and 14? which extend in relatively opposite directions,the ear 14 being positioned to engage the underside of the arm 11 whenthepawl swings into the upright or stopping position,

V thus limiting the swing of the pawl in such direction and sustainingthe force applied to it by the tangent arm 2 during reverse movementthereof. The weight. of the pawl '14 is so distributed thereinrelatively to the pivot pin 13 as to cause the pawl to, remain byposition shown by the full lines in Fig. 3 or in the upright operativeposition shown in said figure, thecenter of weight of the pawl passingover the pivot pin 13 when the pawl is moved from either of saidpositions to the other position. V

. The stop pawl 14 is mounted'at one side of the shaft 5, and this shaftis provided preferably at theend thereof nearits supporting bearing 15,with a lug or eccentric portion16 which is fixed on said shaft so as to.turn therewith and is provided, at one side of the shaft, with a slot 17which extends in the plane of rotation of said shaft,

and the lug or eccentric portion 16carries a pivot pin 18 which islocated eccentrically or at one side of the center of the shaft v5 andpivotally supports a controlling pawl 19 which is mounted to rock freelyin the slot 17 The pawl 19 is provided at one end with a finger 20 whichprojects laterally therefrom and intersects the plane ofthe stop pawl14,

' and the-controlling pawl is capable of rocking relatively totheportion lfi through an being limited by the engagement of a shoulder 21at its opposite end with the opposite side of the portion 16 as shown bythe full lines in Fig. 3. The pawl 19 is formed; with an enlargement 19at the outer side of its pivot 18 whereby the weight of this pawlwill-be so distributed that while the shaft 5 is rotating in a forwarddirection during the normal operationof the meter and the pivot 18 isbeing carried around the shaft 5'past the stop pawl, the end of thepawlv 19 carrying the finger 20.will lie bygravity against the lug oreccentric portion 16, as shown in Fig. 4, so that the finger20 willtravel in a relatively small circle and itwillclear the stop pawl 14,thusleaving the latter in its lowered or inoperative position where itwill clear the tangent arm 2, but when the shaft 5 is rotated in theopposite direction, as takes place when themeter mechani m is operatedin a reverse manner, the controlling pawl '19 will be held the path'ofthe finger 20, and as the pawl 19 moves over the top of the-shaft 5, thefinger 20 thereon engages the upper side of the ear 14 onthe stop pawl,and further advance ofthe controlling pawl 19, due to the continuedreverse rotation of the shaft 5 and while the shoulder21 on thecontrolling pawl continues to bear on the eccentric porti'on16,causesthe finger 20.to bear on the ear 14 and to force the stop pawl 14tofrock fromthe full line position into the dotted line position shownin Fig. 3, after which,-the

arm .20'dropsofi the ear 14 andthepaw1 19 rocks bygravity into itsopposite position, the stop pawl 14 then projecting upwardly into thepath of the tangent arm 2 so that it will-arrest backward rotationthereofwhen it comes into engagement with the stop pawl.-

The operation is as follows WVhile the meter is operating in the nor malmanner, the tangent arm 2 rotates in the direction indicated by thearrow in Fig. 1

and the indicator operating shaft 5 rotates in the direction indicatedby the arrow in Fig. 4, the stop pawl 14 then lying by gravity in itslowered position on the supporting arm 11 below and clear of the pathof'the tangent arm and the directionof rotation ofthe shaft 5 causingthecontrolling pawl 19 to be held by gravity in a position where thefinger 20 thereon will travel past the stop pawl in a rel- I thedirection indicated by the arrow in Fig. 3.

Owing to the worm and gear connection between the tangent arm crank 1andthe dial or indicator-operating shaft 5, the tangent arm will make avariable number of revolutions before the controlling pawl 19 is broughtto the upper side of the shaft 5, but the controlling pawl as it islifted and approaches the upper side of the shaft 5, is held by gravityin the position shown in Fig. 3, the finger 20 thereon then swinging ina relatively larg- 1 er circle about the shaft 5 as a center, and whenthe controlling pawl reachesa position above the shaft 5, the fingerQOthereon engages the upper side of the ear l l on the stop pawl 14, andthe further movement of the controlling pawl, due tothe continuedreverse rotation of the shaft 5, causes the finger 20 to bear downwardlyupon the ear 1? and to rock the stop. pawl 14 into its upright operativeposition, as shown by the dotted lines in Fig.3, the stop pawl beingthen in the path of the tangent arm 2, and the tangent arm will engagethe stop pawl and its rotation will 'be thereby arrested, backwardoperation of the meter mechanism being thereby arrested. Operation ofthe meter mechanism in the normal forward direction after its reverseoperation has been arrested will cause the tangent arm to come againstthe opposite side of the upstanding stop pawl 14 and restore it to itsnormal in operative position as shown in Fig. 4.

While the back check will thus arrest reverse or backward operation ofthe meter mechanism and thereby preclude fraudulent;

use of the meter, it will protect the meter mechanism or its parts fromstrain or injury in the event excessive back pressure is temporarily oraccidentally applied to themeter outlet line, as when the gas entrainedtherein rises in temperature and thus tends to expand and increase inpressure and flow back through the meter, or should the workmaninadvertently apply pressure to the meter outlet line instead of themeter inlet line for cleaning purposes, thus causing the meter tooperate in a reverse direction. Since the worm and gear connectionbetween the crank 1 and the indicator operating shaft 5 is a reductiongearing which enables a number of revolutions of the crank 1 to takeplace during each revolution of the shaft 5, the crank 1,

' which is driven from the measuring bellows or diaphragms and actuatesthe valves thereof, may rotate reversely a large number of times underthe influence of such back pres sure and back flow .of gas before thecon- I trolling pawl is brought into position-to set the stop pawl inposition to arrest backward rotation of thetangent arm, the metermechanism being thus permitted to operate in a V Y i reverse directionto an extent which will be suflicient to compensate for the amount ofthe temporary back flow of gas through the meter and thus protect theparts thereof from strain or inju-ry,-before such reverse operation ofthe meter mechanism is arrested. For

example, in'using the improved back check in a meter havinga wormwith a'singlethread on the crank 'l and a cooperating gear having twelve teethon theshaft 5, which is a normal gear ratio used inmeters, the tangentarm'will 'be permitted to make a minimum of three or four reverserevolutionsand as many as sixteen or seveiiteenreverse revolutionsbefore its reverse inotionis arrested, thusp'e'rmitting backfiow'ofgasthrou-gh the meter to the extent of the largen'umber ofreverse revolutions allowed the tangent arm before it is stopped,therebyprotecting the meter mechanism against temporary excessive backpressure, although precluding continued reverse operation of the meter,whereasback checks previously proposed or used allowed only from afraction of one reverse revolution to a maximum of two reverserevolutions of the'tangent arm to take place before arresting itsmotion, and such a small extent of reverse motion allowed the tangentarm in such back checks is insufiicient, in many cases, to compensatefor such back pressure and the amount of back flow ofgas throughthemeter, with the result that strain is applied to many of the workingparts'of the meter mechanism and such parts are frequently broken. Thepresent invention thus obviates this serious objection to meters asheretofore generally constructed. k 4

Since the stop pawl 14 normally lies in stationary position on the upperside of its sup-' porting arm '11 and the controllingpawl clears thestop pawl during the 'normalfoperation of the meter, there will be'noclicking or other objectionable sound produced by the backcheck'durinthe normal'opera- I tion of the meter.

I claim as my nvention 1. In a meter comprising meter mechanism having amember movable therewith, a back stop pawl normally clear of the pathoffisaid member, and'a gravity controlled element set 1 during. reversemovement of saidmember to move said pawl into the path'of said member tostop it, 2. In a meter compr sing meter mechanism having a membermovable therewith-,a backstop pawlnorma-lly clear of the p'ath'of saidmember, and an element held inoperative relatively to said-pawl-bygravity1dujring movement of said member in one direction and movable bygrav ty into posltion to cooperate with said pawl to setit in stoppingrelation with said member during reverse movement of the latter. a

' 3. In a meter comprisingmeter mechanism having members connected tomove at relatively different speeds, a back stop device movable 'intostopping relation with themember moving 7 at the relatively higherspeed, and a controlling'device for said back stop device actuated bythe member moving at therelatively lower speed. I I

a 5. In a meter comprising meter mechanism having members connected tomove at relatively different speeds, a back stop device normallyinactive but movable into stopping position relativelyto the membermoving at the relatively higherspeed, and a controlling device actuatedby the member moving at the relatively lower speed and set, by movementof said members in reverse direction, to

move said back stop device into stopping position. I

6. In a meter comprising a tangent arm and a crank carrying it, and ashaft connected thereto to operate at a relatively lower speed, a backstop pawl movable into and out of the path of the tangent arm, and acontrolling pawl carried by said shaft and operative upon said back stoppawl 'to move it into the path of the tangent arm.

. 9. In a meter. comprising a tangent-arm and a crank carrying it, and ahorizontal indicator actuating shaft connected by reduction gearing tothe tangent arm crank to rotate at a relatively lower speed relativelythereto, a back stop pawl normally clear of the path of the tangent armand movable into the path thereof to stop, it, and a controlling pawlpivoted eccentrically on said horizontal shaft and movable past saidstop pawl, the controlling pawl being rockable by gravity into aposition to clear the stop pawl during forwardrotation of the horizontalshaft and rockable by gravity into a position toengage the stop pawl andmove it intothe-path of the tangent arm during reverse rotation of thehorizontal shaft. 7 a T In testimony whereof I havehereunto set myhand.a

, V DAVID N. LAMBERT.

'7. In a meter comprising a'tangentarm and acrank carrying it and ahorizontal shaft connected thereto to" rotate at a relatively lowerspeed,-a back stop pawl movable into the'path of the tangent arm, and acontrolling pawl carried by said horizontal shaft and set by gravityduring reverse rotation of said shaft, into position to move the backstop pawl into the path of the tangent arm.

'- 8. In a meter comprising'a'tangent arm and a crank carrying it and ahorizontal shaft connected thereto and rotating therewith, a backstop-pawl movable into the path of the tangent arm, 'and atcontrollingpawl pivoted on said horizontal shaft eccentrically thereof and movableby gravity, during forward and reversei rotation of said horizontalshaft, into positions to respectivelyclear'said pawl and to move saidpawl into the path ofthe tangent

